Potentiometric membrane

One important application of amperometry is in the construction of chemical sensors. One of the first amperometric sensors to be developed was for dissolved O2 in blood, which was developed in 1956 by L. C. Clark. The design of the amperometric sensor is shown in Figure 11.38 and is similar to potentiometric membrane electrodes. A gas-permeable membrane is stretched across the end of the sensor and is separated from the working and counter electrodes by a thin solution of KCl. The working electrode is a Pt disk cathode, and an Ag ring anode is the... 

Loew LM (1988) How to choose a potentiometric membrane probe. In Loew LM (ed) Spectroscopic membrane probes, vol 2. CRC Press, Boca Raton, FL... 

Loew LM (1994) Characterization of potentiometric membrane dyes. In Blank M, Vodyanoy I (eds) Biomembrane electrochemistry. Washington DC, American Chemical Society... 

V.V. Cosofret and R.P. Buck, Recent advances in pharmaceutical analysis with potentiometric membrane sensors. Crit. Rev. Anal. Chem. 24, 1-58 (1993). 

In some applications, silver/silver chloride or calomel electrodes are considered cumbersome to use and maintain. More importantly, they are extremely difficult to miniaturize particularly with regard to their combined use with potentiometric membrane electrodes (see Section 18a.4.5.4) that have been fabricated into highly miniaturized and compact screen-printed sensor arrays for clinical use. Thus, several reference electrodes are manufactured with the same polymeric materials that are needed to design the responsive ion-selective membranes [7]. Incorporation of suitable active agents into such membranes leads to potentiometric responses that are ideally independent of the sample... 

How analytical methods deal with interferences is one of the more ad hoc aspects of method validation. There is a variety of approaches to studying interference, from adding arbitrary amounts of a single interferent in the absence of the analyte to establish the response of the instrument to that species, to multivariate methods in which several interferents are added in a statistical protocol to reveal both main and interaction effects. The first question that needs to be answered is to what extent interferences are expected and how likely they are to affect the measurement. In testing blood for glucose by an enzyme electrode, other electroactive species that may be present are ascorbic acid (vitamin C), uric acid, and paracetamol (if this drug has been taken). However, electroactive metals (e.g., copper and silver) are unlikely to be present in blood in great quantities. Potentiometric membrane electrode sensors (ion selective electrodes), of which the pH electrode is the... 

Enantioselective, potentiometric membrane electrodes design, mechanism of potential development and applications for pharmaceutical and biomedical analysis... 

Enantioselective, potentiometric membrane electrodes (EPMEs) are proposed for the potentiometric detection of the enantiomers [2,10]. The advantages of utilization of these electrodes over amperometric biosensors and immunosensors are a longer lifetime, a large working concentration range, no dilution required for the samples and possibility of decreasing of limit of detection by utilization of KC1 0.1 mol/L as internal solution [2],... 

Enantioanalysis of S-captopril using an enantioselective, potentiometric membrane electrode... 

Response characteristics of the enantioselective, potentiometric membrane electrode for S-captopril [1]... 

Table 5.10 summarizes the presently available electrodes categorized as glass, ion-exchange membrane, crystal membrane, and liquid membrane. These electrodes can be used either for direct potentiometric measurements of ionic activity after calibration of the Nemst expression for the particular electrode or to monitor a potentiometric titration when a selected reaction that involves the monitored ion is available. Table 5.10 also indicates the common interfering ions. Several instrument companies are endeavoring to develop potentiometric-membrane electrodes to monitor directly ions in body fluids. 

Rechnitz, G.A. Bioanalysis with potentiometric membrane electrodes. Anal. Chem. 1982, 54, 1194A. 

Arvand, M., Moghimi, A.M., Afshari, A. and Mahmoodi, N. (2006) Potentiometric membrane sensor based on 6-(4-nitrophenyl)-2,4-diphenyl-3,5-diaza-bicyclo 3.1.0 hex-2-ene for detection of Sn(II) in real samples. AnaZ ChimActa, 579 (1), 102-108. 

POTENTIOMETRIC membrane DYES are employed to study cell physiology. The pioneering work of Cohen and his co-workers (1-3) led to the availability of a large number of organic dyes whose spectral properties are sensitive to changes in membrane potential. The applications of these dyes to a variety of problems in cell biology and neuroscience were reviewed in a series of chapters in a recent book (4). The aim of this chapter is to review the characteristics of these dyes as determined in model and cell membranes. 

Application of a suitable potentiometric membrane electrode for detection in ion-chromatography gives a detectability similar and in some cases even better than reported... 

Field-effect Transistors Enzyme FETs and immuno FETs (IMFETs) are based on principles similar to those valid in potentiometric membrane biosensors. The enzyme is immobihzed on top of the ion-selective membrane on the gate of the FET. For construction of ENFETs, usually double-gate FETs are used employing one gate as a reference system, covered only with a layer of the immobilization matrix, and allowing for the real-time compensation of pH modulations, temperature, and drift. Mostly, pH-sensitive FETs (ISFET)... 

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